It's all explained in the original post. On the fifth mission (The GoldCoast one), put all of your money in to it BEFORE the mission. The only mission that changes the formula is the 4th mission, which you need to put money down AFTER the mission. I always create a Quick Save before I start it, put the money down, finish the mission and then sleep for 3 or 4 days and then check the stocks. At around 82% is when they tend to peak, so sell them then. Some people have been able to go higher, but this is just my experience with it.

Well I've got to get my money back up now so it's worth it. I was hoping to double stack the stocks for a nice gain to.

I didn't know the OP was updated because everytime I checked the thread, it only had the first 2 up, so I've just left this page of posts open.